Case Study // Marcol House – Great Portland Estates

Scope of Works

Undertaken on behalf of Great Portland Estates, a key requirement of this project was to allow All Bar One to continue trading. They occupy part of the basement, ground and mezzanine levels, so a robust waterproo­fing was installed onto the existing fi­rst floor slab, with a signi­ficant plant capability including large air intake and extract ducting.

Along the Regent Street and Margaret Street periphery, a six storey high grade II listed façade was retained, totalling 50 meters in length, together with corbelling and balcony features. As a consequence of the retained demise, it was necessary for Erith Contractors to remain flexible in the façade retention solutions – with an external temporary works retention system being developed for part of the Regent Street façade, and an internal façade retention system which incorporated and utilised the permanent steelwork being developed to retain the façade above All Bar One.

Designing the façade

Beneath the footprint of the retained façades are the north bound running tunnels of the Victoria and Bakerloo tube lines which form part of London Underground’s Oxford Street station complex. These imposed restrictions on the foundations to the façade retention systems adopted. Signi­ficant engineering challenges were uncovered during the execution of the project. Erith, in conjunction with Swanton Consulting, was able to lead and manage the required design changes. Such challenges influenced the way the façade had been tied back to the existing steel frame. The presence of column lines which followed the stepped façade, whilst utilising existing floor beams as local transfer structures, conspired to make the transfer of loads from existing to temporary structures more complex.

Post demolition enablement activities including the construction of over 100 meters of underpinning and the removal of all buried obstructions were carried out in readiness for hand over to the main contractor.

“The project has had some difficult challenges not least because of the number of neighbours who each have very different operational requirements and working hours. I would like to thank Erith for working closely with us to ensure that all of the neighbours were kept fully informed and also their requirements accommodated”

Helen Dawson – Great Portland Estates